U.S. patent application number 11/577966 was filed with the patent office on 2009-08-20 for modular humeral prosthesis for an inverted shoulder prosthesis.
Invention is credited to Didier Capon, David Collins, Lieven De Wilde, Anders Ekelund, Laurent Lafosse, Cecile Nerot, Didier Poncet, Ludwig Seebauer, Michael Wirth.
Application Number | 20090210065 11/577966 |
Document ID | / |
Family ID | 34950416 |
Filed Date | 2009-08-20 |
United States Patent
Application |
20090210065 |
Kind Code |
A1 |
Nerot; Cecile ; et
al. |
August 20, 2009 |
MODULAR HUMERAL PROSTHESIS FOR AN INVERTED SHOULDER PROSTHESIS
Abstract
The invention relates to a modular humeral prosthesis for an
inverse shoulder prosthesis, comprising an anatomical shaft (1) and
a separable epiphyseal head (2) which may be angularly orientated
by rotation about the longitudinal axis (XX) of the anatomical
shaft. The anatomical shaft and the epiphyseal head comprise
complementary angular indexing means (11, 28) for relative
rotational fixation.
Inventors: |
Nerot; Cecile; (Reims,
FR) ; Capon; Didier; (Sautron, FR) ; Seebauer;
Ludwig; (Forstinning, DE) ; Ekelund; Anders;
(Bromma, SE) ; De Wilde; Lieven; (Gent, BE)
; Wirth; Michael; (San Antonio, TX) ; Collins;
David; (Little Rock, AR) ; Lafosse; Laurent;
(Annecy Le Vieux, FR) ; Poncet; Didier; (Bron,
FR) |
Correspondence
Address: |
PHILIP S. JOHNSON;JOHNSON & JOHNSON
ONE JOHNSON & JOHNSON PLAZA
NEW BRUNSWICK
NJ
08933-7003
US
|
Family ID: |
34950416 |
Appl. No.: |
11/577966 |
Filed: |
October 25, 2005 |
PCT Filed: |
October 25, 2005 |
PCT NO: |
PCT/FR05/02663 |
371 Date: |
April 28, 2009 |
Current U.S.
Class: |
623/19.14 ;
623/19.12 |
Current CPC
Class: |
A61F 2002/30828
20130101; A61F 2002/30774 20130101; A61F 2002/30617 20130101; A61F
2002/4074 20130101; A61F 2002/30433 20130101; A61F 2002/3071
20130101; A61F 2002/30604 20130101; A61F 2002/4051 20130101; A61F
2250/0097 20130101; A61F 2002/30355 20130101; A61F 2002/30879
20130101; A61F 2002/3054 20130101; A61F 2250/0089 20130101; A61F
2/40 20130101; A61F 2/4014 20130101; A61F 2002/30428 20130101; A61F
2002/4022 20130101; A61F 2/4059 20130101; A61F 2/30767
20130101 |
Class at
Publication: |
623/19.14 ;
623/19.12 |
International
Class: |
A61F 2/40 20060101
A61F002/40 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 25, 2004 |
FR |
0411366 |
Claims
1. Modular humeral prosthesis for an inverted shoulder prosthesis,
characterised in that it comprises an anatomical rod (1) and a
separable epiphyseal head (2) which can be orientated angularly by
rotation around the longitudinal axis (XX) of the anatomical rod;
and in that the anatomical rod and the epiphyseal head comprise
mating means (11, 28) for angular indexing and for the mutual
rotational blocking thereof.
2. Modular humeral prosthesis according to claim 1, characterised
in that the mating means for indexing and rotational locking are,
on the one hand, a plurality of notches (28) provided in a contact
surface (22) of the epiphyseal head (2) making contact with the
anatomical rod (1), disposed in a radial angular distribution
around the longitudinal axis (XX) of the anatomical rod and, on the
other hand, a lug (11) carried by the other contact surface (7) of
the anatomical rod (1) making contact with the epiphyseal head (2)
and capable of cooperating with said notches.
3. Modular humeral prosthesis according to either claim 1 or claim
2, characterised in that the anatomical rod (1) comprises at least
one longitudinal rib (6) for rotational blocking.
4. Modular humeral prosthesis according to any one of claims 1 to
3, characterised in that the anatomical rod (1) and the epiphyseal
head (2) comprise mating means (8, 23) for locating and guiding in
rotation; and in that the epiphyseal head and the anatomical rod
are joined together by a coaxial screw (3) to the means of guidance
in rotation.
5. Modular humeral prosthesis according to any one of claims 1 to
4, characterised in that the joint between the anatomical rod (1)
and the epiphyseal head (2) is intended to be located inside the
humerus when the prosthesis is in position in order to respect the
deltoid tension.
6. Modular humeral prosthesis according to claim 5, characterised
in that the contact surface (22) of the epiphyseal head (2) extends
laterally beyond the anatomical rod (1), whatever the angular
orientation of the anatomical rod (1).
Description
[0001] The present invention relates to a modular humeral
prosthesis for an inverted shoulder prosthesis.
[0002] Shoulder prostheses consisting of a humeral prosthesis of
which the epiphyseal portion cooperates with a mating deltoid
component are known. In particular, anatomical shoulder prostheses
in which the humeral prosthesis head is convex are known. These
prostheses respect the orientation and the centre of rotation of
actual joints. However, and in particular if the cap of the
rotators is broken (partially or completely), prostheses of this
type prevent elevation of the arm.
[0003] In order to re-establish the range of internal rotation of
the arm (in particular elevation and abduction), the anatomical
prosthesis is replaced by an inverted prosthesis in which the
epiphyseal head of the humeral prosthesis is concave. An inverted
prosthesis of this type displaces the centre of rotation of the
shoulder and this increases the lever arm of the deltoid muscle and
thus facilitates elevation of the arm. However, this displacement
of the centre of rotation partially limits the internal and
external rotations of the arm. In order to promote the internal
rotation (which allows the patient to place his hand on his back),
the epiphyseal head will be positioned with a retroversion of
approximately 0.degree. (frontal plane).
[0004] In addition to displacing the centre of rotation of the
joint, the inverted shoulder prosthesis changes the angle of
retroversion of the prosthesis relative to the shoulders. This
modification to the shoulder retroversion angle varies from one
patient to another. Therefore, when an inverted shoulder prosthesis
is put into position, it has to be suitably orientated relative to
the patient's individual anatomy. Similarly, it is desirable that
the inverted prosthesis be put into position in such a way that the
displacement of the centre of rotation of the shoulder does not
cause an excessive distension of the deltoid muscle tendons.
[0005] In order to produce inverted shoulder prostheses, it has
been proposed to use a single-piece humeral prosthesis of which the
rod intended to cooperate with the humerus is generated by
revolution and, in particular, is conical. A humeral prosthesis of
this type has the advantage of being able to be orientated as
desired relative to the humerus, but has the drawback of not being
rotationally blocking with respect to the bone, with the result
that the prosthesis is able to move and thus become dislodged over
a period of time.
[0006] To overcome this drawback, it has been proposed to use a
humeral prosthesis of which the rod has an anatomical shape, in
other words a rod of which the cross-section cooperates with that
of the metaphyseal portion of the medullary canal in a well-defined
position. With an anatomical humeral rod of this type, however, it
is necessary to be able to orientate the epiphyseal head of the
prosthesis by rotation around the longitudinal axis of the rod. A
modular humeral rod consisting of an anatomical rod and a separable
epiphyseal head mounted on the anatomical rod by means of a ball
joint, for example, has been proposed for this purpose (EP 1 402
805). This inverted shoulder prosthesis has the drawback of having
an epiphyseal head which extends well above the epiphysis of the
humerus (outside the humeral bone). This significantly increases
the distance between the humerus and the glenoid cavity,
over-tensing the deltoid muscle.
[0007] To avoid excessive extension of the deltoid muscle
ligaments, the patent application US-2004/064187, in particular,
has proposed a modular humeral rod for an inverted shoulder
prosthesis comprising an anatomical rod on which is mounted a
epiphyseal head designed to be integrated inside the epiphysis of
the humerus and which can receive either a humeral head for an
anatomical joint or a humeral head which mates with a concave joint
for an inverted prosthesis. The epiphyseal head of this prosthesis
can be orientated by rotation around the longitudinal axis of the
humeral rod and can be locked in position relative to the humerus
by means of vertical ribs provided in the epiphyseal head and which
cooperate with the internal wall of the humeral canal. This
prosthesis has the drawback of not having means for easy adjustment
of the orientation of the epiphyseal head relative to the
anatomical rod. One of the features of inverted shoulder prostheses
equipped with an anatomical rod is that the orientation of the
epiphyseal head relative to the anatomical rod has to be adapted to
each patient. This orientation, which corresponds to the joint
retroversion angle, can vary from 10.degree. to 30.degree.,
depending on the patient and, in particular, on his age. It is
therefore important to be able to adapt and control the orientation
of the angle of the epiphyseal head relative to the anatomical rod
in each individual case. In addition, when the prosthesis is in
position, the angular adjustment of the epiphyseal head relative to
the rod has to be locked to prevent it from becoming dislodged over
a period of time.
[0008] The problem of locking the epiphyseal head in position
relative to the rod could be solved by using single-piece
anatomical humeral rods. However, the dimensions of the anatomical
rod have to be adapted to the patient's size. In addition, the use
of single-piece anatomical humeral rods would necessitate the
provision of a very large number of rods each corresponding to a
size and a retroversion angle. To reduce the number of prostheses
required to be able to meet the requirements of all patients,
therefore, it is desirable to have modular prostheses in which an
epiphyseal head can be combined with an anatomical rod of adapted
size, and the epiphyseal head can be orientated precisely relative
to the anatomical rod when the prostheses is at rest and this
orientation is secured.
[0009] In addition to this problem of reducing the number of parts
required to meet all the requirements, it is desirable that the
prosthesis can be removed in the event of an overhaul. Therefore,
the humeral rod (adjusted angularly relative to the epiphysis) must
never laterally exceed the epiphysis to allow extraction of the
implant.
[0010] The object of the present invention is to overcome the
drawbacks of known prostheses by proposing a modular humeral rod
for an inverted shoulder prosthesis, which allows the epiphyseal
head to be orientated precisely and securely relative to the
metaphyseal portion of the anatomical rod (to optimize the internal
rotation of the humerus), which may be extractable and which, when
in position, is completely within the humerus to avoid over-tensing
of the deltoid.
[0011] The invention accordingly relates to a modular humeral
prosthesis for an inverted shoulder prosthesis comprising an
anatomical rod which has an anatomical metaphyseal portion and a
separable epiphyseal head which can be orientated angularly by
rotation around the longitudinal axis of the anatomical rod, the
anatomical rod and the epiphyseal head comprising mating means for
angular indexing and for the mutual rotational blocking
thereof.
[0012] The mating means for indexing and rotational blocking are,
for example, on the one hand a plurality of notches provided in a
contact surface of the epiphyseal head making contact with the
numeral rod, disposed in a radial angular distribution around the
longitudinal axis of the anatomical rod and, on the other hand, a
lug carried by the other contact surface of the anatomical rod
making contact with the epiphyseal head and capable of cooperating
with said notches.
[0013] Preferably, the anatomical rod comprises at least one
longitudinal rib for rotational blocking.
[0014] Preferably, the anatomical rod and the epiphyseal head
comprise mating means for locating and guiding in rotation, and the
epiphyseal head and the anatomical rod are joined together by a
coaxial screw to the means of guidance in rotation.
[0015] Preferably, the joint between the anatomical rod and the
epiphyseal head is intended to be located inside the humerus when
the prosthesis is in position in order to respect the deltoid
tension. It is therefore preferable that the contact surface of the
epiphyseal head extends laterally beyond the anatomical rod.
[0016] The invention will now be described in greater detail but in
a non-limiting manner with reference to the accompanying figures,
in which:
[0017] FIG. 1 is an exploded view of a modular humeral prosthesis
for an inverted shoulder prosthesis,
[0018] FIG. 2 is an enlarged view from below of the epiphyseal head
and the upper portion of the anatomical rod of a modular humeral
prosthesis for an inverted shoulder prosthesis,
[0019] FIG. 3 is an exploded schematic section of a modular humeral
prosthesis for an inverted shoulder prosthesis in position within a
humerus.
[0020] FIG. 4 is an enlarged longitudinal section of the upper
portion of the modular humeral prosthesis in FIG. 3.
[0021] The modular humeral prosthesis for an inverted shoulder
prosthesis shown in FIG. 1 comprises an anatomical rod 1, a
separable epiphyseal head 2 which is positioned at the upper end
(or proximal extremity) of the anatomical rod 1, and a screw 3 for
connecting the epiphyseal head 2 to the rod 1.
[0022] The anatomical rod of which the shape is known per se
comprises a generally cylindrical stem 4 which is extended in its
upper portion by a metaphyseal portion 5 which flares upwardly so
as to have a shape which is adapted to the form of the epiphyseal
joint of a humerus with the metaphysis of this humerus. This head 5
constitutes the proximal extremity of the anatomical rod, the
lateral wall of the head 5 of the anatomical rod comprises ribs 6
for blocking in position relative to a humerus in which the rod is
implanted.
[0023] The proximal extremity of the anatomical rod 1 is limited by
a planar surface 7 which corresponds to a section perpendicular to
the longitudinal axis of the anatomical rod. A hole 8 extending
within the anatomical rod and parallel to the axis of this rod is
drilled perpendicularly to the surface 7 delimiting the proximal
extremity. The hole 8 comprises a first bore 9 followed by a
screw-threaded hole of smaller diameter 10. Preferably, the hole 8
and the stem 4 of the anatomical rod are coaxial. The surface 7
further comprises a lug 11 which projects longitudinally relative
to the metaphyseal rod.
[0024] The epiphyseal head 2 is a portion of a sphere delimited by
an equatorial plane 21 and a plane forming an acute angle with an
equatorial plane. Below the equatorial plane 21, the epiphyseal
head 2 comprises a bowl 21A intended to receive a polyethylene or
ceramic cup. This cup is the part which is intended to cooperate
with the mating portion of the prosthesis which will be fixed to
the scapula. The plane forming an acute angle with the equatorial
plane defines a polar surface 22 intended to come into contact with
the end surface 7 of the anatomical metaphyseal rod 1.
[0025] The polar surface 22 comprises a cylindrical lug 23 which
projects from the polar surface 22 and is perpendicular thereto.
The size of this cylindrical lug 23 is adapted so that it can
cooperate with the greater diameter bore 9 of the axial hole 8 in
the anatomical rod and thus locate the epiphyseal head relative to
the anatomical rod. An axial hole 24 for receiving a screw 3
extends through the cylindrical lug 23, the screw 3 extending both
in the hole 24 in the epiphyseal head and in the hole 8 in the
anatomical rod so that it will be screwed into the screw-threaded
portion 10 of the hole 8. The hole 24 comprises a first portion 25
of greater diameter intended to receive the head 31 of the screw
and a portion of smaller diameter 26 intended to receive the body
32 of the screw 3. The cylindrical lug 23 and the hole 8 constitute
means for locating and guiding in rotation the epiphyseal head
relative to the anatomical rod.
[0026] The portion of smaller diameter 26 comprises a first portion
26A of short length having a diameter and a screw thread identical
to the diameter and screw thread of the screw-threaded portion 10
of the axial hole 8, the metaphyseal rod and a second portion 26B
of greater length extending to the point where the hole emerges at
the end of the cylindrical lug 23 and of which the diameter is
greater than or equal to the external diameter of the
screw-threaded portion of the screw 3. The body 32 of the screw 3
comprises, at its extremity, a screw-threaded end 32A which is
capable of cooperating with the screw thread of the screw-threaded
portion 10 of the axial hole 8 in the metaphyseal rod, and a stem
32B connecting the head 31 of the screw 3 to the screw-threaded
end, and having a diameter smaller than the internal diameter of
the first screw-threaded portion 26A of the portion of smaller
diameter 26 of the hole 24 in the epiphyseal head.
[0027] With this arrangement, the epiphyseal head is completely
separated from the anatomical rod by unscrewing the screw. In order
to put the screw in position, it first has to be screwed into the
screw-threaded portion 26A of the hole in the epiphyseal head. This
has the advantage of making the screw integral with this epiphyseal
head while leaving it free in rotation and in translation over a
specific length and thus facilitates manipulation by the surgeon
who is putting the prosthesis in position.
[0028] The polar surface 22 comprises a plurality of notches 28
disposed radially relative to the axis of the cylindrical lug 23
and at a distance from this lug such that, when the cylindrical lug
23 is disposed inside the hole 8 of the anatomical rod 1, the lug
11 situated on the surface 7 of the proximal extremity of the
anatomical rod 1 can cooperate with a notch 28. These notches are
arranged at 10.degree. from one another in a fan and are
complemented by markings which allow the position of the epiphyseal
head 2 relative to the anatomical rod 1 to be determined when the
epiphyseal head is disposed on the anatomical rod and the lug 11 is
within a notch 28.
[0029] In addition, the plane defining the polar surface 22 is
selected so that the diameter of this polar surface is sufficient
for the polar surface 22 to extend laterally beyond the surface 7
of the proximal extremity of the anatomical rod, whatever the
orientation of the epiphyseal head relative to the anatomical rod.
As a result, when the prosthesis is in position in a humerus, the
re-growing bone does not form bands which extend beyond the
proximal extremity of the anatomical rod and therefore does not
prevent extraction of the prosthesis.
[0030] Referring to FIG. 4, the epiphyseal head 2 is able to rotate
about the longitudinal axis XX of the anatomical rod. The axis YY
of the epiphyseal head perpendicular to the equatorial plane 21
intersects the longitudinal axis XX of the anatomical rod 1 at a
point A preferably located on a surface defined by the contact
between the proximal face 7 of the anatomical rod 1 and the polar
face 22 of the epiphyseal head 2.
[0031] Finally, FIG. 3 shows that the length of the anatomical rod
and the dimensions of the epiphyseal head are selected so that,
when the prosthesis is in position, the epiphyseal head is
completely included in the epiphysis of the humerus.
[0032] In order to put a prosthesis of this type in position, the
surgeon begins by preparing the humerus by producing, in a known
manner, an axial hole adapted to receive an anatomical humeral rod
and an epiphyseal head. Then, using an appropriate gauge, he
determines the retroversion which the epiphyseal head will have to
perform relative to the anatomical humeral rod.
[0033] The surgeon then puts in position the anatomical rod then
the epiphyseal head while orientating it at a predetermined angle
and immobilises it in rotation by causing the lug 11 of the
proximal extremity of the anatomical rod to cooperate with the
appropriate groove 28 in the polar surface 22 of the epiphyseal
head. He finally tightens the screw 3 to lock the assembly.
* * * * *